I installed the V Twin 6 1/2" adapters and a pair of Polk Audio DB651 speakers. I am running the RF PBR 300 amp. I was less than impressed with the sound to say the least. So much so, that I took those out and reinstalled the Polk Audio 5 1/4" setup that I replaced. So, without buying several different t6 1/2" speakers, what's the best sounding 6 1/2 speaker that folks have had success with?